Potentiometer resistance and switching means



Dec. 6, 1960 A. RANNIE 2,963,675

POTENTIOMETER RESISTANCE AND SWITCHING MEANS Filed Jan. 31, 1955 m: 115 I25 SEB 7B 5 a -36 Z [1111! i a 39 4'0 37 39 )u 111111 n l: v

United States Pat t" ()fifice 13 33 91 2,

POTENTIOMETER RESISTANCE AND SWITCHING MEANS Arnold Rannie, 1811 Sunnyside Ave., Winston-Salem, N.C.

Filed Jan. 31, 1955, Ser. No. 484,958

6 Claims. (Cl. 338-95) The present invention relates to potentiometers and more particularly to a single resistance ratio potentiometer in which a specially laminated resistance bank of conductive and non-conductive elements provides a contact surface to accommodate a number of brushes which are selectively traversed across the laminated elements to contact a selected portion or position on the laminated surface.

It is conventional in radar equipment and other electronic and electrical applications to employ individual potentiometers in a battery or multiple arrangement maki ing operation and control somewhat difficult and space consumption rather large. Since many of the instruments to which these individual potentiometers are applied are highly sensitive it is essential that the unit construction be accurately controlled. Nearly all potentiometers for these purposes are produced by winding a continuous insulated wire of calibrated resistance about a suitable mandrel and the mandrel is shaped to be placed into a suitable housing or mounting. A brush or contact element may be rotatably or linearly slidable on the housing to engage with the surface of the wound resistance in order to produce the desired value at a selected position. Extreme care must be exercised in winding the insulated wire to insure uniform ratio resistance readings throughout the extent of the potentiometer winding. Prolonged and constant use of the brush contact with the wire convolutions will abrade and wear away the wire and eventually result in fatigue failure. Furthermore, it is common practice to employ only a very limited number of brushes on a single card.:

It is therefore an object of the present invention to provide a single resistance ratio potentiometer in which a number of separate contact brushes may individually function to serve in the place of numerous individual potentiometers.

Yet another object of the present invention is to provide a single potentiometer which is suitable for operating in place of numerous individual potentiometers by having a laminated card formed by conductive and non-conductive elements and a number of brush contacts which may be advanced in guided travel transversely across the elements in a predetermined order.

Still another object of the present invention is the provision of a laminated structure for conducting an electromotive force to and from a variable resistance which is formed of conductive and non-conductive elements with the conductive elements connected electrically by means of a common continuous length of calibrated resistance.

A further object of the present invention is to provide a sine or cosine or a sine-cosine resistance bank suitable for use in potentiometers and in which the bank is composed of individual conductive sheet elements separated by non-conductors with the conductive elements interconnected electrically to a calibrated variable resistance and a linear surface provided by the bank to enable a number of individual contact elements to be moved thereacross transversely over the elements.

Still a further object of the present invention is to provide a means for traversing linearly selective individual brushes of a single resistance ratio potentiometer and a means for making contact selectively with a known predetermined ratio resistance at predetermined fixed intervals of brush travel.

Other objects and advantages of this invention will become more apparent from the following detailed description taken in conjunction with the accompanying drawing in which like characters of reference designate corresponding parts throughout the several views and wherein:

Fig. 1 is a partial perspective view illustrating a portion only of a number of conductive and nonconductive elements stacked in a series;

Fig. 2A is a view in end perspective depicting a completed potentiometer card of sinecharacteristics of the insulated Wire wound card type;

Fig. 2B is a view in end perspective showing an assembled potentiometer card of sine-cosine characteristics of the insulated Wire wound card type;

Fig. 3A is a diagrammatic illustration of a calibrated ratio resistance potentiometer formed by the conductive element, the conducting leads, the brush conductors and V the contact elements associated therewith;

Fig. 3B is a displaced component perspective view of a number of individual rotary contact disk wheels normally mounted to rotate together on a single shaft;

Fig. 4 is a diagrammatic illustration in perspective of a number of brush elements guided transversely across a laminated level surface of the laminated plate elements;

Fig. 5 is an additional rotary contact disk wheel employed in conjunction with a sine-cosine potentiometer;

Fig. 5A illustrates a connection to the center tap of a potentiometer having sine-cosine characteristics.

Referring to the drawings there is shown in Fig. 1 a laminated band 10 constituted by a series of individual conductive plates or sheets 11 on each of which there is integrally formed a lug 12 and a series of non-conductive separator sheets 13 which are alternately positioned between conductive plates. The total number of conductive and non-conductive sheets stacked together in laminated form will depend primarily upon the desired magnitude of ratio resistance readings utilized in the specific potentiometer application. Each of the thin conductor metallic plates or sheets 11 may have a thickness in the order of .001 of an inch with the separator non-conductor sheets of substantially similar thickness.

It is proposed that each laminated conductor bank 10 may be constituted by a large number of individual sheets or plates approximating the number of turns or convolutions presently being employed on insulated wire wound type resistance potentiometer cards. Thus it will not be uncommon to employ several hundred or even several thousand individual conductive and non-conductive plates for each bank.

In assembling the sheet elements together into a compact laminated structure the individual plates are held together by long non-conductive or non-magnetic rods 14 which are passed transversely through suitable openings 15 in the plates. Suitable fixtures may be designed for stacking the elements to facilitate insertion of the rods and also to permit registry of the openings throughout the large number of elements. Openings 15 in the conductive plates may be slightly larger in diameter than the corresponding openings in the non-conductive platesv Subsequent to final assemblage of the elements into a laminated structure, the top surface 16 constituting a track or guideway over which the contact brushes may be moved transversely, is ground or otherwise mechanically worked to provide a level, smooth guideway transversely across the plate in order to permit unimpeded travel of the contact brushes, to be described hereinafter.

"Lugs 12, positioned along the lower edge of the conductive plates, may be arranged in an indexed displaced or staggered relationship along the plate edge opposite the level surface in order to facilitate fastening of a calibrated resistance 17 to each lug 12.

The resistance 17 is made of an uninsulated or bare wire having a predetermined resistance for particular points along its linear length. Resistance 17 may be secured by spot welding to the individual lugs. Calibration of the resistance 17 will be described hereinafter.

In the conventional sine-cosine cards used in potentiometers a variable resistance is obtained by winding convolutions of wire about a mandrel having a definite triangular configuration to produce the sine or cosine values. As shown'in Figs. 2A and 2B the triangular configuration of Fig. 2A presents a right triangular card and Fig. 2B represents an isosceles configuration, each producing a resistance'of'the desired magnitude in the potentiometer in which the cards are employed.

In the present invention the assembled laminated structure of conductive and non-conductive plates of substantially uniform size are stacked contiguous to each other and may be manipulated so that the bare resistance wire 17 may be welded to the conductive plate lugs in any desired sequence with the length of resistance Wire varying in a predetermined manner in order to produce a variable or progressively varying resistance throughout the length of the laminated structure. For example, one end of resistance wire 17 may be welded to an end conductive plate lug and the reach or extent of resistance wire having a known resistance is calibrated so as to yield a known resistance for the given length before it is attached as by welding to the next succeeding conductive plate lug in the laminated structure. In the event that it is desired to produce a structure which would yield results similar to either of the cards shown in Figs. 2A or 2B it is merely necessary to calibrate the resistance wire 17 so that the resistance between the attaching lugs will correspond substantially to the resistance increments produced by winding an insulated wire above the card or mandrel in Figs. 2A and 2B.

Considering the conventional wire wound cards 20 and 21 of Figs. 2A and 2B further, card 20 is provided with fixed end conductors 22 and 23 and a single brush element 24 which may be moved transversely across the surface of the wire convolutions to obtain the desired resistance. Card 21 is provided with similar end conductors 25 and 25 and in addition has a center tap lead 27 in order to obtain the characteristic sine-cosine values. A single brush 28 may traverse the top of the card 21 and will remain in contact with the wire convolutions. Actually the wire insulation on the top portion of each of the cards is removed in order to expose the bare wire for contact with the moving brush contact element.

It will be evident that a structure that will yield the same characteristics as the potentiometer resistance cards 20 and 21 may be produced by stacking the conductive plates in a series and then calibrating the resistance wire 17 according to the desired resistance and attaching the calibrated length of the resistance to the conductive plate lugs 12. End lead conductors and a single brush element may be provided with the brush element traversing the top level surface 16 of the laminated structure so that this type structure may be substituted for the conventional potentiometer cards. However, it is further provided in this invention that by utilizing the laminated conductive plates and calibrated resistance in combination with a switching assemblage that a combination ratio reading potentiometer capable of substituting for a number of individual potentiometers may be provided.

Fig. 3A illustrates a schematic representation of one embodiment of the invention in which the calibrated resistance 17 is shown with substantially equal length coils or loops and the loops are connected in some selected or predetermined resistance value to the conductive plates in a desired sequence, as described above. Welded to the plate lugs 12 and resistance 17, in a selected order, are a number of conductor leads 1 through 8. Although the leads 1 through 3 are represented as being connected at the terminal portion of the resistance 17 and the plates in a successive order, they may very well be staggered or spaced apart so as to omit several intervening plates depending upon the resistance desired for the output. The free ends of the leads 1 through 8 are connected to individual brush elements 1A through 8A which brush elements may be circumferentially spaced from each other when assembled to function with the disk wheels A or C. Continuity brush elements 1B through 8B, corresponding to the mating brush elements 1A through 8A, are maintained in spaced relation to brush elements 1A through 8A for sequential make and break contact duringa cycle of rotation of the disk wheels.

Upon suitably spacing the brush elements 1A through 8A and 1B through 8B in close proximity to rotating disk wheels A and C so that a conductive contact will bridge the gap between A and B brushes a voltage may be trans mitted between the brushes in a desired sequence.

In the illustrated arrangement of Figs. 3A and 3B, the disk wheels A, B, and C are mounted to rotate on a single shaft 30 with the brush elements 1A through 8Aand 1B through'SB adjacent to disk wheels A and C. Each disk wheel is formed of conductive segments 31 and insulated segments 32 around the wheel periphery with the help of the disk wheel insulated from the shaft 30. Upon rotation of the disk wheel A in a clockwise direction the gap between brushes A and B will be insulated from each other initially when an insulated segment 32 is presented between the series of brushes. As the disk wheel rotates further the conductive contact 31 will wipe the brush elements 1A and 1B, 2A and 213, 3A and 3B, 4A and 4B in sequence. It will be apparent that by synchronizing the disk wheels A and C the sequence of contact closing may be such that 1A and 18 together with SA and 58 will close simultaneously and similarly with the other contact brushes in the series.

In order to make the potentiometer function as a variable ratio reading unit thelength of laminated structure 10 between ends may be provided with a number of brush elements, only four being shown, 35, 36, 37 and 38, which are threadably engaged by the individual lead screws 39 in order to traverse the individual brush elements 35 through 38 transversely across the level surface of the laminated structure. Suitable guide rods 40 are provided to prevent lateral movement of the brushes during linear travel along the plane surface 16.

The brush members 35 through 33 correspond to the brush elements 9', 10, 11 and 12' of Fig. 3A wherein the brush elements may be displaced along the level surface 16 of the laminated structure 10 to transmit a determinable voltage along the conductive plates which correspond to the plate position with respect to the calibrated resistance 17. Movable brush elements 9', 10, 11' and 12' have conductor leads similar to the conductor leads 1 through 8 which leads are connected to the brush elements 9A through 12A, respectively. Brush elements 9A through 12A and the corresponding mating brush elements 9B through 12B are spaced substantially similar to the spacing for the other brush elements. It Will also be recognized that the disk wheel B which is similar to the other disk wheels A and C will function ina similar manner as disk wheel B will be mounted on the same shaft 39. An established selective order orsequence for closing an opening contact between all the brush elements may be established so that simul taneous contacts may be made between 1A1B, 9A--9B and 5A--5B, or some other desirable combination or sequence may be used.

Conventional drive means, not shown, may be provided for rotating the shaft 30 at the recommended speed. Also suitable mechanical drive means or synchros may be used to drive the lead screws 39 to position the brush elements 35 through 38 in some selected sequence along the track 16.

In those applications where it is desirableto use a center tap corresponding to the sine-cosine card 21 the calibrated resistance 17 may be provided with a conductor lead 45 to which the brush elements 13A through 16A and 13B through 16B are used in a manner similar to the other brush elements. It is to be understood that an additional disk wheel D will be mounted on the shaft 30 to function in conjunction with the center tap connection 45 and the center tap connection may be used with the slide brush elements 35 through 38 and the disk wheel B, all in the same system.

When desirable the disk wheels ganged on a single shaft may be run in a bath of oil or other heat transfer medium to dissipate any heat that may be generated by the friction of the brushes against the rapidly rotating disk wheels.

Normally the securement of the bare or uninsulated calibrated resistance to the individual plate lugs requires careful treatment. In assembling the plate elements only the top portions are clamped together thereby permitting the elements to be separated at the lower lug portions sufficiently to provide space to weld the bare resistance to the individual lugs. With the non-conductive separators being longer than the conductive plates and lugs, the lugs and connections are insulated from each other.

To eliminate unnecessary elongation of the bare wire resistance and so as to maintain a uniform resistance throughout its length, the bare wire is spread out linearly and not spooled. One end of the bare wire is welded to a first thin plate of the laminated series and before the next point is welded a ratio reading point is established along the wire by using a Wheatstone bridge and galvanometer to calibrate the resistance which will be affixed at the next weld point and so on for the extent of the conductive plates. Periodically at the welded points along the bare wire a Formvar coating is applied and dried before continuing to complete the other welded points and positions.

The completed laminated potentiometer formed of a large number of thin conductive plates may be of any length or width, the width being dependent largely on the number of brushes to be used in lateral positions. Definite ratio readings may be set at fixed or predetermined points along the full length potentiometer larninations and the laminations may be calibrated also in conjunction with the travel of the movable brushes.

Obviously many modifications and variations may be made in the construction and arrangement of the elements in the light of the above teachings Without departing from the real spirit and purpose of the invention. It is, therefore, to be understood that within the scope of the appended claims many modified forms of structure as well as the use of equivalents may be reasonab ly included and modifications are contemplated.

What is claimed is:

1. In a multiple ratio reading potentiometer apparatus, the improvement comprising in combination, a laminated structure having a plurality of individual conductive and non-conductive plate elements arranged in parallel contiguous form, a continuous calibrated resistance engaging selective conductive plates to yield predetermined voltages derived from an external voltage source, at least one conductor contact communicating with adjacent terminal ends of the calibrated resistance at one end of the contact, a contact element connected at the other end of each conductor contact, and rotating means for periodically engaging the contact elements to voltage.

2. In a multiple ratio reading potentiometer apparatus, the improvement comprising, in combination, a laminatedstructure having a plurality of individual conductive plates and non-conductive elements stacked contiguously, a calibrated resistance of preselected values spaced at intervals throughout the resistance length, said resistance being connected to the conductive plates at determined resistance intervals, a conductor connected at one end to at least a single conductive plate adjacent the ends of the laminated structure, pairs of contact elements, one of said elements of a pair of contact elements being connected to the other end of each of said conductors, the other of said elements of a pair of contact elements being spaced from the first element, to form a gap therebetween, and means for periodically bridging the gap bee tween contact elements permitting electrical conductivity from a selective conductive plate to the contact elements.

3. In a multiple ratio reading potentiometer apparatus, the improvement comprising, in combination, a laminated structure having a plurality of individual conductive plates and non-conductive elements stacked contiguously in a series, a calibrated resistance of preselected values spaced at intervals throughout the resistance length, said resistance being connected to the conductive plates at determined resistance intervals, a plurality of conductors connected at one end of each of said conductors to selective conductive plates, a plurality of contact elements movable transversely along the laminated structure in di rected paths, a second conductor connected to each of said movable contact elements at one end, pairs of contact elements, one of said elements of a pair of contact elements being connected to the other end of one of each of said plurality of conductors, the other of said pair of contact elements being spaced from the first element to form a gap therebetween, and switching means having spaced conductive segments spaced selectively for bridging the gap between contact elements sequentially.

4. In a multiple ratio reading potentiometer apparatus, the improvement comprising, in combination, a laminated structure having a plurality of conductive plates and nonconductive elements stacked contiguously alternately in a series, a calibrated resistance with preselected resistance values spaced at intervals along the resistance length, sai-d resistance being connected to the conductive plates at determined resistance intervals, a plurality of conductors connected at one end of each of the conductors to the calibrated resistance at determined resistance intervals, brush elements movable transversely across the series of conductive plates and non-conductive elements in linear spaced apart paths, second conductors connected at one end to the movable brush elements, pairs of contact elements corresponding to the number of said first mentioned conductors, said contact elements being spaced apart in a selected series for sequential operation, each of said pair of contact elements being spaced apart from each other to form a gap therebetween and switching means having spaced conductive and non-conductive elements for sequentially bridging the gap between contact elements to transmit a determinable voltage impressed on the laminated structure from an external voltage source and whereby the ratio readings may be varied depending on the position of the movable brush elements along the laminated structure.

5. In a multiple ratio reading potentiometer apparatus, the improvement comprising a series of conductive and non-conductive sheets alternately positioned contiguous to each other and in compact laminar relation, said series of sheets forming at one edge a level track, a continuous calibrated resistance connected to selective conductive sheets at predetermined ratio reading intervals, a plurality of disks mounted to rotate together, each of said disks having selectively spaced contact areas, contransmit a ductors connected to the spaced contact areas on the disks and communicating with selective positions along the series of laminated conductive sheets, brush members on said conductors for sequentially engaging the spaced contact areas on the disks to transmit a predetermined voltage value as the disks rotate and the contact areas engage with the brush members.

6. In a multiple ratio reading potentiometer apparatus, the improvement comprising a series of conductive and non-conductive sheets alternately positioned contiguous to each other and in compact laminated relation, said series of sheets forming a level track along one edge transversely across the sheets, a calibrated resistance connected to selected conductive sheets, a plurality of disks mounted to rotate together, each of said disks having selectively spaced contact areas, said areas on the disks being displaced in different phase angles with respect to each other, conductors corresponding to the spaced contact areas on the disks engaging selective fixed References Cited in the file of this patent UNITED STATES PATENTS 411,947 Wightman Oct. 1, 1889 1,533,611 Respess Apr. 14, 1925 1,785,479 Dubilier Dec. 16, 1930 1,881,130 Proctor Oct. 4, 1932 2,634,330 Gaudio Apr. 7, 1953 2,674,717 Ponsy Apr. 6, 1954 2,696,577 Smith Dec. 7, 19541 

